Method of heating the interior and structure of large vessels or enclosures

ABSTRACT

Hot gases, consisting of the products of combustion of a removable external burner, are injected as a divergent stream into the interior of a vessel or enclosure at high velocity. The gases may be injected with a spinning action. Diluent air or other gases may be entrained with the products of combustion in the burner which may be a tubular burner having a mouth inserted in an opening in the wall of the vessel or enclosure. The injected gases circulate within the vessel or enclosure to produce and maintain uniform elevated temperatures over all or part of the interior surface of the vessel or enclosure. The temperature of the injected gas stream may be controlled by varying the supply of diluent gas.

United States Patent 1191 Hemingway et al.

[ 1 Dec. 16, 1975 [75] Inventors: Maurice Hemingway, Mirfield;

Trevor Ward, Dewsbury, both of England [73] Assignee: Hotwork Limited, Dewsbury,

England [22] Filed: Dec. 14, 1972 21 Appl. No.: 314,980

[30] Foreign Application Priority Data Dec. 15, 1971 United Kingdom 58277/71 [52] US. Cl. 431/9; 29/487; 432/12 [51] Int. Cl. F23B 7/00 [58] Field of Search 431/9, 182, 185; 432/222, 432/12; 148/127; 29/487 [56] References Cited UNITED STATES PATENTS 2,705,627 4/1955 Norgaard 148/127 X Hortvet 4.32/12 X Sikora 148/127 X Primary Examiner-Charles J.. Myhre Assistant Examiner-William C. Anderson Attorney, Agent, or FirmEdwin E. Greigg [5 7] ABSTRACT Hot gases, consisting of the products of combustion of a removable external burner, are injected as a divergent stream into the interior of a vessel or enclosure at high velocity. The gases may be injected with a spinning action. Diluent air or other gases may be entrained with the products of combustion in the burner which may be a tubular burner having a mouth inserted in an opening in the wall of the vessel or enclosure. The injected gases circulate within the vessel or enclosure to produce and maintain uniform elevated temperatures over all or part of the interior surface of the vessel or enclosure. The temperature of the injected gas stream may be controlled by varying the supply of diluent gas.

4 Claims, 1 Drawing Figure in F 1 AV AV AV AV AV AV AV AV A US. Patent Dec. 16, 1975 3,926,543

'AIIII gillHillllllllllllllllllll METHOD OF HEATING THE INTERIOR AND STRUCTURE OF LARGE VESSELS OR ENCLOSURES This invention relates to a method of heating the interior and structure of large vessels, or enclosures, which involves the production and maintenance of uniform elevated temperatures over all or part of their interior surfaces, the method being of the kind in which hot gases, consisting of the products of combustion of a removable external burner, are injected into the interior of the vessel or enclosure at high velocity and are circulated within or through the interior of the vessel or en closure.

It has been found that injection into the interior of the vessel or enclosure of a stream of hot gases which emerges from the burner substantially parallel to the axis of the burner outlet nozzle at a velocity high enough to raise the temperature of the structure of the vessel or enclosure at the rate required for some heat treatment processes, such as stress-relieving or annealing of welded fabricated metal vessels or shell structures which have to withstand high working pressures, can result in the structure of the vessel or enclosure being heated unevenly. Injection of such a stream of hot gases at a velocity which ensures uniform heating of the structure of the vessel or enclosure is unlikely to result in the temperature of that structure being raised at the required rate.

It is an object of this invention to provide a method of the kind described which will enable the temperature of the structure of a vessel or enclosure to be raised uniformly at a higher rate than is reasonable if it is raised by the injection into the interior of the vessel or enclosure of a stream of hot gases which emerges from the burner substantially parallel to the axis of the burner outlet nozzle.

According to this invention there is provided a method of the kind described wherein the hot gases are injected into the interior of the vessel or enclosure as a divergent stream.

Preferably gases within the stream are injected into the interior of the vessel or enclosure with a spinning action.

The removable external burner, in which fuel is burned to produce the products of combustion, may be a tubular burner having a mouth inserted in an opening in the wall of the vessel or enclosure, diluent air or other gas being entrained with the products of combustion to provide a gas current having a total volume flow greater than that of the products of combustion alone. The burner may conform to that described in applicants copending U.S. patent application Ser. No. 314,981, filed on Dec. 14, 1972, now US. Pat. No. 3,834,857.

The temperature of the gas current may be controlled by varying the supply of diluent gas. A1tematively, the fuel and combustion air may be mixed at the point of combustion of the burner, the temperature of the products of combustion being controlled by varying the quantity of fuel supplied to the burner.

One way in which the method according to the invention may be carried out will now be described by way of example. Fuel is burned in a tubular burner, the mouth of which is inserted into an opening in the wall of the vessel or enclosure to be heated, the products of combustion being directed at high velocity with a spinning action through the burner mouth to form a divergent stream of hot gases which creates an extensive disturbance of the atmosphere within the vessel or enclosure, causing currents in which the products of combustion are entrained and distributed substantially evenly over the whole of the vessel or enclosure, thus producing even and progressive heating.

The tubular burner preferably has a convergent portion terminating in the outlet nozzle, which may be flared outwardly, so that the velocity of the combustion products of the burner is increased as it passes through the outlet nozzle, and clearance may be provided around the burner mouth to enable diluent air to be entrained and drawn into the vessel or enclosure by the stream of combustion products. The quantity of diluent air may be varied by altering the clearance to modify the temperature of the combined stream of combustion products and diluent air without altering the ratio of fuel to combustion air, so that mixing of the gaseous or atomised fuel and air before they reach the point of combustion can be used. Alternatively the fuel and combustion air may be mixed at the point of combustion of the burner in such a way that, as described in the Complete specification of our US. Pat. No. 1,000,231, an optimum mixture for combustion can be ensured at some parts of the combustion zone regardless of the overall ratio of fuel to air, and the temperature of the combustion products can then be controlled by varying the quantity of fuel supplied to the burner independently of the quantity of combustion air.

An example of a large welded fabricated metal pressure vessel which can be stress-relieved by a method according to this invention is illustrated by the accompanying drawing.

1 claim:

1. A method of heating the interior and structure of large enclosures utilizing the hot exhaust gases formed as the result of combustion in a burner which is externally removable with respect to the enclosure being heated, comprising injecting as a divergent stream into the interior of the enclosure at high velocity and thereby causing to be circulated within and through the interior of the enclosure, the hot gases of combustion along with diluent air or other gas so that the gas current has a total volume flow greater than that of the products of combustion alone, thereby producing and maintaining uniform elevated temperatures over at least part of the interior surface of the enclosure.

2. A method as claimed in claim 1, wherein the improvement further comprises injecting the hot gases into the interior of the enclosure with a spinning action.

3. A method as claimed in claim 1, wherein the improvement further comprises varying the supply of diluent gas in order to control the temperature of the gas current.

4. A method as claimed in claim 1, wherein the improvement further comprises mixing the fuel and combustion air at the point of combustion of the burner, and varying the quantity of fuel supplied to the burner in order to control the temperature of the products of combustion. 

1. A method of heating the interior and structure of large enclosures utilizing the hot exhaust gases formed as the result of combustion in a burner which is externally removable with respect to the enclosure being heated, comprising injecting as a divergent stream into the interior of the enclosure at high velocity and thereby causing to be circulated within and through the interior of the enclosure, the hot gases of combustion along with diluent air or other gas so that the gas current has a total volume flow greater than that of the products of combustion alone, thereby producing and maintaining uniform elevated temperatures over at least part of the interior surface of the enclosure.
 2. A method as claimed in claim 1, wherein the improvement further comprises injecting the hot gases into the interior of the enclosure with a spinning action.
 3. A method as claimed in claim 1, wherein the improvement further comprises varying the supply of diluent gas in order to control the temperature of the gas current.
 4. A method as claimed in claim 1, wherein the improvement further comprises mixing the fuel and combustion air at the point of combustion of the burner, and varying the quantity of fuel supplied to the burner in order to control the temperature of the products of combustion. 